1. Field of the Invention
The present invention relates to a liquid-jet head which pressurizes a liquid supplied to pressure generating chambers communicating with nozzle orifices by piezoelectric elements to jet liquid droplets from the nozzle orifices, and relates to a liquid-jet apparatus. More particularly, the present invention relates to an ink-jet recording head which ejects ink droplets from nozzle orifices, and relates to an ink-jet recording apparatus.
2. Description of the Prior Art
In an ink-jet recording head, in which pressure generating chambers that communicate with nozzle orifices ejecting ink droplets are partially constituted of vibration plates, these vibration plates are deformed by piezoelectric elements to pressurize ink in the pressure generating chambers, and the ink droplets are ejected from the nozzle orifices, two types of recording heads are put into practical use. One is a recording head using piezoelectric actuators of a longitudinal vibration mode, which expand and contract in an axis direction of the piezoelectric elements, and the other is a recording head using piezoelectric actuators of a flexural vibration mode.
In the former type, the volume of each pressure generating chamber can be changed by abutting an end surface of the piezoelectric element against the vibration plate, and manufacturing of a head suitable to high density printing is enabled. On the contrary, there are required a difficult process of cutting and dividing the piezoelectric element in a comb tooth shape in accordance with an array pitch of the nozzle orifices and work of positioning and fixing the cut and divided piezoelectric elements to the pressure generating chambers. Thus, there is a problem of a complex manufacturing process.
On the other hand, in the latter type, the piezoelectric elements can be fabricated and installed on the vibration plate by a relatively simple process of adhering a green sheet as a piezoelectric material while fitting a shape thereof to that of the pressure generating chambers and sintering the green sheet. However, a certain area of the vibration plate is required due to use of the flexural vibration, thus there is a problem that a high density array of the piezoelectric elements is difficult.
Meanwhile, in order to solve such a disadvantage of the latter recording head, as disclosed in Japanese Patent Laid-Open No. Hei 5 (1993)-286131, a recording head is proposed, in which an even piezoelectric material layer is formed over the entire surface of a vibration plate by a deposition technology, the piezoelectric material layer is cut and divided into a shape corresponding to that of pressure generating chambers by a lithography method, and piezoelectric elements are formed so as to be independent of each other for each pressure generating chamber.
The recording head described above has the following advantage. The work of adhering the piezoelectric elements to the vibration plate is eliminated, and the piezoelectric elements can be fabricated and installed by the precise and simple method that is the lithography method. In addition, a thickness of each piezoelectric actuator can be thinned to enable a high-speed drive.
In the ink-jet recording head described above, a semiconductor integrated circuit (IC) or the like for driving the piezoelectric elements is required, and this IC is mounted in the vicinity of the ink-jet recording head. Specifically, heretofore, a method has been adopted, in which the IC is disposed in the vicinities of the piezoelectric elements, and the piezoelectric elements and the IC are wired by wire bonding or the like.
However, particularly, as recording density has been increased, it has been a subject in miniaturization of the recording head that a mounting space for the IC or the like and a space for wiring the piezoelectric elements and the IC or the like should be secured.
Note that, naturally, a similar soultion to the above-described one exists not only for the a method of manufacturing the ink-jet recording head ejecting ink droplets but also in a method for manufacturing another liquid-jet head ejecting a liquid other than ink.
In consideration of circumstances as described above, the object of the present invention is to provide a liquid-jet head in which a wiring structure is simplified to achieve miniaturization and a liquid-jet apparatus.
A first aspect of the present invention that attains the foregoing object is a liquid-jet head including a passage-forming substrate in which a pressure generating chamber communicating with a nozzle orifice is defined and a piezoelectric element composed of a lower electrode, a piezoelectric layer and an upper electrode on one surface of the passage-forming substrate with a vibration plate interposed therebetween, the liquid-jet head comprising: a sealing plate joined to a piezoelectric element side of the passage-forming substrate and having a piezoelectric element holding portion, the sealing plate hermetically sealing a space secured in a region facing the piezoelectric element to an extent not to hinder a movement thereof; and a lead electrode provided on the passage-forming substrate and drawn out from any of the electrodes of the piezoelectric element to an area outside of the piezoelectric element holding portion, wherein the sealing plate has a plurality of penetrated holes penetrating therethrough in a thickness direction thereof, and on an inner surface of each penetrated hole, a wiring electrode is provided, one end thereof being connected to the lead electrode outside of the piezoelectric element holding portion, and other end thereof being connected to a drive wiring extended from a drive circuit for driving the piezoelectric element on an opening edge portion of the penetrated hole on a side opposite the passage-forming substrate.
In the first aspect, each lead electrode drawn out from the electrode of the piezoelectric element is extended to a surface of the sealing plate on the side opposite the passage-forming substrate by the wiring electrode formed in the relatively micro penetrated hole. Therefore, the lead electrode and the drive wiring can be connected in a relatively small space, and the miniaturization of the head can be achieved.
A second aspect of the present invention is the liquid-jet head according to the first aspect, characterized in that the wiring electrode is continuously provided to an opening edge portion on a passage-forming substrate side of the penetrated hole.
In the second aspect, the lead electrode and the wiring electrode are connected easily and securely.
A third aspect of the present invention is the liquid-jet head according to any one of the first and second aspects, characterized in that the wiring electrode is filled in the penetrated hole.
In the third aspect, the region corresponding to the opening of the penetrated hole of the sealing plate is plugged with the wiring electrode. Therefore, the wiring electrode and the drive wiring can be connected on the region facing to the penetrated, and the head can be further miniaturized.
A fourth aspect of the present invention is the liquid-jet head according to any one of the first to third aspects, characterized in that the wiring electrode is formed of a thin film.
In the fourth aspect, even in the relatively small space, the wiring electrode can be formed easily and securely.
A fifth aspect of the present invention is the liquid-jet head according to the fourth aspect, characterized in that the wiring electrode is formed by any of plating and sputtering.
In the fifth aspect, the wiring electrode composed of the thin film can be formed relatively easily.
A sixth aspect of the present invention is the liquid-jet head according to any one of the first to fifth aspects, characterized in that the drive wiring is composed of a bonding wire.
In the sixth aspect, the wiring electrode and the drive circuit can be connected easily, and the manufacturing efficiency is enhanced.
A seventh aspect of the present invention is the liquid-jet head according to any one of the first to sixth aspects, characterized in that the sealing plate is composed of a single crystal silicon substrate.
In the seventh aspect, the penetrated hole can be formed with relatively high precision in high density.
An eighth aspect of the present invention is the liquid-jet head according to any one of the first to seventh aspects, characterized in that the sealing plate also serves as a reservoir forming plate having a reservoir portion at least partially constituting a reservoir made to communicate with the pressure generating chamber.
In the eighth aspect, a reservoir having a relatively large volume can be formed, and the simplification of the structure can be achieved.
A ninth aspect of the present invention is the liquid-jet head according to any one of the first to eighth aspects, characterized in that the pressure generating chamber is formed by carrying out anisotropic etching to the single crystal silicon substrate, and each layer of the piezoelectric element is formed of a thin film by a lithography method.
In the ninth aspect, the liquid-jet head having the nozzle orifices in high density can be manufactured relatively easily in a large quantity.
A tenth aspect of the present invention is a liquid-jet apparatus comprising the liquid-jet head according to any one of the first to ninth aspects.
In the tenth aspect; the miniaturization of the liquid-jet apparatus can be achieved.